Electrical devices are provided with a power supply cord. It is possible that the power supply cord or the operating equipment get damaged. If such a damage is not detected, an endangerment of the operators arises, as for example an electrical shock and a security problem, as for example a fire hazard due to overheating.
Pursuant to standard DIN-VDE 0701-0702, inter alia, the following tests have to be carried out in regular time intervals:
1. Resistance measurement, in particular of the protective earth (RSL).
2. Protective earth current, wherein it is measured whether in a connected device or its power supply cord a protective earth current, i.e. a residual current, occurred.
3. Visual inspection.
The problem underlying the present invention is to provide a power supply cord for which a damage can easily and reliably be detected through a user.